This invention relates generally to improvements in actuator assemblies for use in computer disk drives. More particularly, the present invention relates to an improved actuator assembly having a labyrinth seal capable of eliminating or minimizing actuator bearing lubricant migration or out-gassing into the computer disk drive.
In recent years, microcomputer equipment, particularly the so-called personal and desk top computers, having become extremely popular for a wide variety of business, educational and other uses. Such computers commonly include a main central processor unit having one or more memory storage disks for storage of data. In many modern computers the storage disk or disks, sometimes referred to as "hard disks", are provided as part of a Winchester-type disk drive unit having the storage disks supported in a stack on a rotary spindle within a substantially sealed disk drive housing. The disks are rotatably driven in unison by a small spindle motor, and one or more electromagnetic heads on a movable actuator are displaced by a moving coil, limited rotation D.C. motor to traverse surfaces of the rotating disks for purposes of reading and writing data. Such Winchester-type disk drive units are generally preferred in comparison with so-called floppy-type disk drives due to their higher memory storage capacities and faster operating speeds.
The actuator used in Winchester-type disk drive units resembles the traversing arm of a common phonograph, and typically includes an arm assembly designed to carry the electromagnetic heads which are used to read and write data on the disk stack. A coil is mounted to the actuator opposite to the arm assembly to interact with a magnet assembly for purposes of controlling the movement and positioning of the electromagnetic heads. As current moves through the coil, it reacts with the magnet assembly to move the entire actuator assembly.
The actuator is typically mounted for pivotal movement about a pivot shaft which is fixed relative to a housing for the computer disk drive. A bearing assembly, usually comprising one or more bearings, is disposed between the pivot shaft and the actuator. The bearings must be lubricated to ensure their proper operation, but it is important that the bearing lubricant not be permitted to migrate from the bearing assembly into contact with other components of the computer disk drive since this could cause a malfunction. For this reason, double-shielded bearings are often used in order to minimize actuator bearing lubricant migration. It has been found, however, that this alone is not enough to prevent the undesirable migration of the bearing lubrication, particularly due to the high centrifugal forces to which the actuator and bearing components are subjected during normal operation of the disk drive unit.
Accordingly, there has been a need for an improved actuator assembly construction which is capable of more efficiently eliminating or minimizing any actuator bearing lubricant migration or out-gassing into the hard disk drive unit. Such an improved actuator assembly should be capable of being efficiently and economically incorporated into most standard-design hard disk drive assemblies, and minimize any additional manufacturing steps for the actuator assembly in comparison with similar actuator assemblies without the improvement. Preferably, a seal is needed which does not interfere with pivotal movement of the actuator about the pivot shaft, and yet reduces the amount of air flow and blocks the travel of small particles between high and low pressure areas through the actuator assembly, and particularly the bearing assembly thereof. The present invention fulfills these needs and provides other related advantages.